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Mephenaqualone

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Subjective Effects
Interactions
History & Culture
Mephenaqualone molecule structureMephenaqualone molecule structure
Open in Piru
Chemical Class
Quinazolinone

Mephenaqualone is a central nervous system depressant of the quinazolinone class1 with sedative and hypnotic effects. It is an analogue of methaqualone,1 sharing a similar chemical structure1 and pharmacological effects. It differs structurally from methaqualone by having a 2-bromophenyl group at the third position of the quinazolinone ring.

Dosage & Duration

Log in Piru

Dosage

Doses are population estimates that vary widely between individuals.

Threshold0.5 mg
Light0.5-1.5 mg
Moderate1.5-2.5 mg
Strong2.5-4 mg
Heavy4+ mg

Duration

Onset30-40 minutes
Come Up5-10 minutes
Peak2-4 hours
Offset10-15 hours
After Effects6-12 hours
Total15-20 hours

Subjective Effects

Subjective Effects not written up yet

Pharmacology

Pharmacodynamics

Mephenaqualone acts as a positive allosteric modulator of GABA receptors, enhancing their activity in the brain and nervous system. This action contributes to its sedative, hypnotic, and muscle-relaxant effects.

Pharmacokinetics

Absorption & half-lifenot documented yetMetabolitesnone documented yet

Interactions

Interactions not written up yet

An unlisted combination is an unknown one, not a safe one. Check a dedicated combination chart before mixing.

Check TripSit

Tolerance

Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.

Full Tolerance
Tolerance to mephenaqualone develops rapidly with repeated use, with tolerance to its sedative-hypnotic effects developing within a few days of repeated administration.
Cross Tolerance

All GABAergic depressants

Harm Potential

Addiction & Dependence

Psychological

High

Mephenaqualone is described as highly addictive and associated with significant abuse potential. Repeated exposure can quickly produce tolerance, prompting users to take larger amounts to obtain comparable effects.

Physical

High

Physical dependence develops with prolonged use. Abrupt discontinuation can lead to withdrawal symptoms including increased anxiety, insomnia, and potential seizures, consistent with GABAergic substance withdrawal.

Toxicity

Respiratory

Overdose can cause respiratory depression, which may become life-threatening particularly when combined with other CNS depressants such as alcohol, opiates, or benzodiazepines.

Seizure Risk

Seizures may occur during withdrawal following abrupt discontinuation after prolonged use, consistent with the withdrawal profile of other GABAergic substances.

History & Culture

History & Culture not written up yet

Legality

International

Legal status outside Germany is largely undocumented and may differ under local designer-drug or analog laws.

By Country

Not scheduled1
Germany flagGermanyNot scheduled

References

Citations

  1. EWS_AT/EU_10.10.2025. Ärztekammer für Wien / Gesundheit Österreich GmbH (2025). https://www.aekwien.at/documents/d/wien/ews_at_eu_10-10-2025123
  2. Gesetz über den Verkehr mit Betäubungsmitteln (Betäubungsmittelgesetz — BtMG), § 1 Betäubungsmittel. gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/btmg_1981/__1.html1
  3. Betäubungsmittelgesetz, Anlage I (zu § 1 Abs. 1) — nicht verkehrsfähige Betäubungsmittel. gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/btmg_1981/anlage_i.html1
  4. Betäubungsmittelgesetz, Anlage II (zu § 1 Abs. 1) — verkehrsfähige, aber nicht verschreibungsfähige Betäubungsmittel. gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/btmg_1981/anlage_ii.html1
  5. Betäubungsmittelgesetz, Anlage III (zu § 1 Abs. 1) — verkehrsfähige und verschreibungsfähige Betäubungsmittel. gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/btmg_1981/anlage_iii.html1
  6. Siebenundzwanzigste Verordnung zur Änderung von Anlagen des Betäubungsmittelgesetzes, BGBl. 2026 I Nr. 150. recht.bund.de (n.d.). https://www.recht.bund.de/bgbl/1/2026/150/regelungstext.pdf?__blob=publicationFile&v=11
  7. Neue-psychoaktive-Stoffe-Gesetz (NpSG), current consolidated text. gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/npsg/BJNR261510016.html1
  8. Neue-psychoaktive-Stoffe-Gesetz, Anlage 1. gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/npsg/anlage_1.html1
  9. Neue-psychoaktive-Stoffe-Gesetz, Anlage 2. gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/npsg/anlage_2.html1
  10. Arzneimittelverschreibungsverordnung (AMVV), current consolidated text and Anlage 1. gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/amvv/BJNR363210005.html1

Article Status

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